A guide to thorn melon farming in Kenya
The thorn melon is locally known as passion mwitu, parachichi mwitu or passion lenye tete maji. Other common names are kiwano, jelly melon or African horned cucumber. It produces edible fruits that have distinctive stippled skin and spiky protrusions. The fruits are peeled and eaten in either the immature or the mature stages, made into juice and leaves also used as a vegetable. In Kenya the fruits are targeted for export markets in Europe and are sold in supermarkets and local markets.
The fruits lack flavour which severely limits its potential as an eating fruit, however they are gaining a lot of importance and production in Kenya is expanding due high demand as a consumers become awareness of its medicinal and nutrients attributes (vitamin C, potassium and iron). It is said to be good for management of high blood pressure, diabetes and obesity. When ripe, it has a yellow orange colour skin and a lime green jelly-like flesh. It also used as a decorative ornamental fruit. Fruits have a long shelf life of up to 6 months.
Steps in thorn melon Production
Thorn melon is cultivated on farms and it also grows naturally in the fields and in the bush. It adapts well in the semi arid areas warm to hot regions. It grows well at an altitude between 210 to as high as 1800 above sea level. The plants are also grown in green houses due to their high market value. The local variety is the main species grown.
- Site selection
Select a planting site with rich, well-drained soil and full sunlight exposure. The plant requires warm to hot conditions and does not do well in cold areas. The soils should be well drained with high organic matter. Clay or loamy soils with a pH range of 6.0 to 6.5 are best for production. Thorn melon is a climber hence requires an area near a trellis or fence to promote climbing. In green house production plants are trained on posts however pollinators such as bees should be introduced at the time of flowering.
Horn melon is propagated by seed. Choose a well developed ripe healthy fruit from the vine to extract seed. Scoop-out the contents consisting of seed and pulp. Seed germination may be improved by softening the seed coat. The seed together with the pulp is ferment for 1 to 3 days in a plastic container. The fruit seed is then thoroughly washed after which it is dried in the shade and sown as soon as possible. Germination of seed can also be improved by priming. This involves soaking the seed in warm water for one hour before planting. Germination occurs within 2-3 weeks. Seed may be sown directly or seedlings are raised in the nursery or trays and are transplanted when they have two true leaves.
Direct planting: 3-4 seeds/hole are planted to a depth about 2 cm and covered with a layer of soil. Rouging is done after 5-7 days to remove excess seedlings to maintain one plant per hill if planted directly in the field.
Spacing: In the green house a spacing of 60 cm x 60 cm can be used while up to 1m apart may be used.
- Fertilizer and Manure: Compost, manure or inorganic fertilizers can be incorporated depending on soil conditions.In poor soils general fertilizer e.g. NPK 17:17:17 can be applied as a basal fertilizer at planting. Top dressing is recommended 3 weeks after germination with nitrogenous fertilizer and potassium fertilizer e.g. Murate of potash can also be added to improve the fruit quality
- Training /trellising
The plants within the greenhouse can be trained upwards and supported by sisal strings which are tied to a wire 2 meters above the ground. Pruning is done to leave 3 stems per plant
- Irrigation: The frequency of irrigation depends on prevailing weather, soil type, and stage of crop development. At flowering and fruiting stage, a more frequent irrigation will be necessary.
- Weeding: Timely weeding is important to prevent diseases such as the cucumber mosaic virus and tobacco ring spot virus.
Maturity and Yield: The fruit matured in 3-4 months under field conditions. Stems of horned melon die back at the end of the growing season while the fruits remain attached and continue ripening to a bright orange colour. They may be harvested over successive months. Immature fruits may be harvested at any time during the growing period. One plant in the greenhouse environment produced an average of 10 fruits. Shelf life is up to 6 months.
Packaging: The fruit has spines/thorns which can result in fruits pierce each other, thus shortening their storage life. Fruits should packed in single layers in crates and layers separated e.g. by dry banana leaves. The banana leaves served as protective pads to ensure that the fruits did not brush against each other, hence reducing the chances of fruit injury.
Diseases and pests: Thorn melons are susceptible to cucumber mosaic virus, tobacco ring spot virus, tomato ring spot virus, watermelon mosaic virus, fusarium wilt.
The viral diseases can be prevented by vectors such as aphids and melon flies, white flies and planting the crop away from the host plants in the cucurbit family such as cucumber, courgettes, and pumpkins. The plants are tolerant to root-knot nematodes, powdery mildew.
Crop rotation is also important for diseases control.
Challenges in production:The thorn melon fruit is has to be grown on its own portion of land, due to its spreading nature unlike other fruits and plants which can be intercropped. Seed production is not yet commercialized hence this can be a limiting factor in production.
Advice to potential thorn melon growers
There is need to produce based on the demand since in some areas demand is low due to lack of awareness about the fruit value. However there is potential for market as a result of promo